Variable ratio transmission



July 13, 1965 R. T. ERBAN VARIABLE RATIO TRANSMISSION 3 Sheets-Sheet 1Filed Feb. 11, 1963 INVENTOR. fi

July 13, 1965 R. T. ERBAN 3,194,088 VARIABLE RATIO TRANSMISSION FiledFeb. 11, 1963 3 Sheets-Sheet 2 INVENTOR.

July 13, 1965 R. T. ERBAN 3,194,088

VARIABLE RATIO TRANSM I S S ION Filed Feb. 11; 1965 3 Sheets-Sheet 3CONTROL *1 IN PUT SHAFT 24 com rnouz OUTPUT SHAFT VARIABLE -RATIO TRAN5- Cour-Ron 5.17 l-lllll a "-1-" INV EN TOR.

United States Patent 3,194,088 VARIABLE RATIO TRANSMISSION Richard T.Erban, 14533 Bay side Ave, Flushing 54, N.Y. Filed Feb. 11, 1963, Ser.No. 257,57 17 Claims. (Ci. 74-6ll) This invention relates in its generalaspect to variable speed transmissions in which power is transmitted bythe tractive forces of rolling contacts between the peripheries ofcoaxially spaced races or wheels and the surface of rotatable discspositioned around and pressed against the preipheries of the wheels.

In known devices of this type the driving shaft is in most casesconnected to one of the coaxial wheels and. the driven shaft isconnected to the other. The output speed can be selected and variedbetween a maximum which is above the input speed and a minimum which maybe as low as a fraction of the input speed but which is always greaterthan zero. These transmissions have therefore a limited ratio range andit is not possible to transmit anything but insignificant amounts ofpower at or even near zero speed because zero speed requires the drivenwheel to be positioned at the center of the disc surface where no properrolling action can take place. The ensuing rubbing friction between thedisc center and the wheel periphery causes heat, rapid wear andprogressive destruction of the contacting surfaces.

1 To avoid these (lifl'lClllilBS, it has been proposed to combine such atransmission of limited range with a dilferential gear system byconnecting one each of the orbit gears ofthe differential to one each ofthe two wheels of the variable speed system, and connecting the planetcarrier of the differential to the output or driven shaft. Thiscombination has an infinite ratio range and permits to maintain outputspeeds at zero or near to it without encountering the aforementioneddefects through rubbing friction at the center of the discs. However, asa result of the circulation of power between the differential gear andthe wheel-disc system which takes place at high internal rotationalspeeds there are considerable frictional losses over a part of the ratiorange which cause heat and which reduce the accuracy of maintaining apredetermined speed ratio under load conditions, and this is detrimentalin the application of such systems in servocontrol-mechanisms as Well asfor Integrators. A further drawback is the fact that the characteristicof control motion versus speed ratio isa hyperbolic function,nonsymmetrical with respect to the point of Zero speed and of differentsensitivity to both sides of zero. control mechanisms it is greatlydesired to have a straightline characteristic of uniform sensitivity andsymmetrical to the zero point. The relatively high cost of adifferential gear system plus the fact that changes of the scope orextension of the ratio-range cannot be obtained without replacingpractically the entire differential system are additional disadvantagesof these combination systems.

It is therefore an object of this invention to create a structure for avariable speed transmission comprising a pair of co-axial wheels and atleast one disc in tractive rolling contact therewith, which will withoutthe use of a differential or planetary gear system provide a controlover the output speed through a speed range that includes zero speed andeven reversing of the output speed by stepless ratio change. A furtherobject is to create a structure which does possess a straight-linecontrol characteristic, that is, a control where the output speed is instraight line-through-zero proportionality with respect to the shiftingmotion of the control member. The shifting motion of the control memberis the axial displacement of the disc with respect to the positions ofthe co-axial wheels.

In many 3,194,088 Patented July 13, .1955

ICC

A still further objectis a structure in which the elements complementingthe basic wheels and disc system are of simple design, economical tomanufacture, and so arranged that they can easily be interchanged forthe purpose of altering the scope of the ratio-range of the transmissionat a minimum of cost.

A still further object is a transmission system in which the full lengthof shifting movement produces a reduced amount of variation of theoutputspeed, that is, a change of output speed of perhaps 5% or less withrespect to the input speedso that the accuracy of speed control is verysubstantially increased while maintaining at thev the transmissionsystem under load conditions.

These objects, and some others which will hereafter be pointed out, areobtained through novel structures which are illustrated by way ofexamples in the drawings attached hereto in which FIG. 1 is alongitudinal section through an embodiment of my invention.

FIG. 2 is a transverse sectional view taken along the line P-P of FIG. 1looking in the direction of the arrows, the upper portion being brokenaway and shown in section taken along the line N-N.

FIG. 3 isa schematic view of a section along M--M of FIG. 1.

FIG. 4 is a schematic diagram illustrating the conditions of speed andmotion on the face of the disc 3 in FIG. 1 as seen from below.

FIG. 5 is a schematic diagram of a gear train similar to that of FIG. 3,showing only the pitch circles.

FIG. 6 illustrates in longitudinal section a special gear train whichincludes a clutching device.

FIG. 7 illustrates schematically .a longitudinal view of the relativepositions of the basic elements of the transmission shown in FIG. 1.

FIGS. 8, 9 and 10 are schematic views as seen from below of the disc 3in FIG. 7 illustrating the speed diagrams for three distinct axialpositions of the disc with FIG. 15 illustrates schematicallyalongitudinalsection of a structure in which the output speed iscontrolled by the basic shifting means and modified by an additionalcontrol parameter.

FIG. 16 illustrates various speed diagrams obtainable by the systemshown in FIG. 15. a

FIG. 17 illustrates schematically a longitudinal section of anotherembodiment of my invention which includse two additional controlparameters.

FIG. 18 illustrates some of the speed and control characteristics thatmay be obtained by the structure shown in FIG. 17.

Inspection of FIG. 1 discloses that the input shaft .5

is in permanent driving connection with both of the coaxial wheels 1 and2 respectively so that the rotational speed of each of these wheels isat all times controlled by the driving shaft. There are established twobranches of power flow, one between the shaft 5 and the wheel 1 snegossthrough the key 4, and the other between the shaft and the wheel 2through the gear train 35-36-38-9. The gear 35 is keyed to the shaft 5and the gear 9 is in torque transmitting connection with the wheel 2through the rotatable sleeve 6. The gears 36 and 38 are freely rotatableupon their respective shafts 37 and 39 and serve as transfer gearsbetween gear 35 and gear 9, modifying the speed and direction ofrotation between gear 35 and gear 9 in predetermined relationship.

7 This gear train is schematically shown in FIG. 3 where only the pitchcircles are drawn, substantially as they would appear in a section ofFIG. 1 along M-M. If the shaft 5 is supposed to be rotating clockwisewhen observed from the end of the shaft at the. left side, then the gear35 when seen from MM will appear rotating counter-clockwise. This isindicated in FIG. 3 by an arrow. The size of the pitch circle of gear 35is marked by the radius r35 in FIG. 3, the radius of the pitch circle ofgear 9 of FIG. 1 is marked r9 in FIG. 3, and similarly the other gearsin FIG. 3 are identified by the radii of their pitch circles r36 and 138respectively. Inspection of FIG. 3 shows that the gear 36 rotatesclockwise and since it meshes with gear 38 this latter rotatescounterclockwise. The peripheral'speed of gear 38 is still the same asthat of gear 35, and this is transmitted to gear 9 which rotatesclockwise, that is, opposite to gear 35, and at a reduced speed ofrotation. If 11 is the rotational speed of gear 35, and similarly n isthe rotational speed of gear 9, this speed in; is given by lation is thesame for the FIG. 1 up to and including FIG.

of the drawings; also, in all of these named figures the wheel 2 rotatesin'a direction opposite to that of the wheel 1. Referring again to FIG.1, the wheel 2 is fastened to the sleeve 6 which in turn is journalledby means of the bearings 7 and 8 upon the input shaft 5. The bearing Sisof a design which locates the sleeve 6 axially with respect to the shaft5. The left end of the sleeve 6 extends into a flange that carries thegear 9. Contacting the peripheries of both wheels are three discs ordifierential wheels 3 each of which is rotatably supported by anindividual bearing 12 mounted on a radial stub-axle 14 extending from ahexagonal carrier or a central hub 11. The shaft 5 passes freely througha central opening of the carrier or hub 11.

Each disc 3 is provided on its outer side with a thrust bearingcomprising the balls 15 and the ball-race 16. An adjustable nut 17 isthreaded upon an extension of the axle 14 for adjusting the axialposition of the thrust bearing 15, 16, together with the disc 3 radiallyinwardly towards the peripheries of the Wheels 1 and 2 in order tomaintain the correct amount of pressure in the contacts which isrequired to transmit tractive forces through the rolling contactsbetween the wheels and the disc.

Only one such disc 3 is shown in FIG. 1 although the transmission hasthree discs 3 as illustrated in FIG. 2. It is understood that in orderto equalize the pressure of the rolling contacts a plurality of discsuniformly spaced along the periphery of the wheels may be used. Thisbalancing of radial contact pressures is highly desirable and has beendescribed in previous patents including my US. Patent 2,057,482.

The hub or carrier 11 which has one radial arm for each of the discs 3is freely rotatable about the longitudinal axis of the shaft 5, and isconnected to the output shaft 1th by three arms 19 of the flange 18. Thehub 22 which forms part of the flange 18, is slidable axially upon thehollow sleeve 24, an extension of the shaft 10. A key 23 (or suitablesplines upon 24) transmits the torque from the hub 22 to the sleeve 24and the shaft 10. A hearing 31 positioned in the housing wall 32supports the shaft 1%. Pilot bearings 26 and 28 support the right sideend of the input shaft 5 from the hollow end of shaft 10. The left sideend of shaft 5 is supported through the hearing 29 from the housing wall30. This housing wall also carries the shafts 37 and 39 respectively ofthe transfer gears 36 and 38.

Referring now to FIG. 4, which is a diagrammatical view of the disc 3 ofFIG. 1 as seen from below, the contact between wheel 1 and the surfaceof the disc is denoted C and similarly, the contact of wheel 2 isdenoted as C The center of the disc 3 is denoted C The straight linewhich extends through these three points is marked XX. The lines 41 and42 indicate the traces or intersection lines of the central planes ofrotation of Wheel 1 and wheel 2 respectively with the plane of thesurface of disc 3. The line 40 is the trace of a plane which containsthe geometric axis of rotation of the disc 3 and is perpendicular to thesurface of the disc 3. It is now possible to indicate the peripheral (orlinear tangential) speed of the wheel 1 in the contact point C by thevector V which extends from C to the point A. Since it was assumedheretofore that the shaft 5 and the wheel 2 rotate clockwise as seenfrom the left end, it follows that the upper portion of the periphery ofwheel 1 (in FIG. 1) moves out of the plane of the drawing towards theeye of the observer. In the third angle projection of FIG. 4, thisdirection is represented by the vector V going up from the axis X-X. Thetangential contact speed of the wheel 2 is then going in the oppositedirection, that is, downwards from the axis XX in FIG. 4 and illustratedby the vector V extending from contact point C to B. The relative lengthof V with respect to V represent the speed reduction between the shaft 5and the wheel 2 and corresponds to the ratio between the pitch radii1'35 and r9 respectively.

For the purpose of the following explanation of the operation it is nowassumed that the disc 3 with its central opening and bearing 12 istemporarily replaced by a flat plate having its surface in the sameposition as the disc 3 was, this plate being so supported that it isable to rotate about any point of its surface and also to move in anydirection parallel to its surface. This plate' is now contacted by thetwo wheels 1 and 2. in the contact points C and C respectively. Thesetwo points (C and C determine a straight line XX. The point C whichbelongs to the plate surface is now subject, through the rotatingperiphery of the wheel 1, to a traction force in the direction of thevector V and therefore tends to move in the direction and with a speedcorresponding to the vector V This motion is at right angles to the axisX-X and upwards from C Similarly the point C which belongs to the platesurface tends to move in the direction and with the speed determined bythe vector V It is seen that all surface points upon the line X-X nearthe point C tend to move upwards while the points near the point C tendto move downwards. Since the direction of movement of all these pointsare parallel to each other (all are perpendicular to the line X-X) andsince the individual speeds vary in value from a positive to a negativemaximum, it follows that between the two extreme positions C and C theremust be a point C where the motion changes its direction from positiveto negative and the speed at right angles to the line XX is Zero.Further, since no motion has been imposed upon the plate surface ineither direction lengthwise with the line X-X, it follows that the pointC has no motion either at right center.

angles to the line X-X nor parallel to it. The point C therefore has nolateral motion in any direction and stands still, it is a pole, orepicenter, around which the plate surface rotates counter-clockwise,driven upwards at the right side of the center by the forces of thevector V and driven downwards at the left side of the center by theforces of the vector V It is to be noted that this epicenter is notestablished or determined by any material axis that forms part and islocated at any point of the surface of the plate. Its position upon theplate surface isdetermined solely by the position of the two contactpoints C and C and by the direction and size of the force vectorstransmitted to the surface in these two points. If these two contactpoints are displaced across the surface of the plate, while keepingtheir relative spacing as well as the direction and size of the forcevectors acting in these two points, the epicenter will move with thedisplacement of the contact points always keeping its same relativeposition with respect to the contact points C and C The exact positionof the epicenter C is the intersection of the line X-X with a straightline connecting the end points A and B of the speed vectors V and V Ithas been shown heretofore that under the conditions as illustrated inFIG. 4 the epicenter has no motion either along the line X--X or atright angles thereto. If we now replace the substituted freely movabletheoretical plate by the original disc 3, and place it so that itsgeometrical center C coincides with the position of the epicenter C itwill be seen that the disc 3 rotates around its geometrical center C(with stub-axle 14) while the center C remains stationary, having nomotion lateral to the line XX, nor parallel to it.

Now, if as a next step, the geometrical center C of i the disc isdisplaced along the line X-X, so that it is at a definite distance fromthe epicenter C this places the geometrical center C in a part of theplane surface which is subject to forces acting at right angles to theline X-X due to the rotation of the plane surface around the epi- If thedisc center C finds itself between the epicenter C and the point C thedirection of motion imparted to the center C will be upwards from theline X-X while for positions of the center C to the left of theepicenter the direction of motion will be downwards from the line XX.The force tending to move the disc center C laterally with respect tothe line X-X causes the disc 3, its bearing 12 and its axle 14 to rotateabout the axis S-S (FIG. 7), which is also the geometric axis of theshaft 5 in FIG. 1. The linear tangential speed of the disc center C(FIG. 4) with the disc in the postion denoted 3' (FIG. 4) is obtained asthe length of the speed vector V from the point C to point D, measuredin the same scale as the speed vectors V and V The number of revolutionsof the disc center C together with the disc and its bearings 12 and15-16 around the geometrical axis of shaft 5 (the axis SS in FIG. 7) isfound as the linear tangential speed (V in FIG. 4) divided by thecircumference of the circular path of the center C around the axis S-S(FIG. 7). Since the center C lies in the plane of the surface of disc 3,the distance of the point C from the geometrical axis SS is the same asfor the points C and C and the circumference is of the same length forall these points. Therefore, the length of the vector V expresses at thesame time linear tangential speed in the scale of vector V androtational speed in the same scale as vector V when it is considered asrepresenting the rotational speed of the wheel 1. The vector V istherefore a measure of the speed n ofthe output shaft 10. FIG. 4 showsan arbitary position 3' for the disc 3 with its physical center at C Therelations resulting from various positions of the disc center along theline X-X will be more fully discussed onhand of FIGS. 7 to 10 inclusive,under the condition that the two Vectors V and V remain unchanged as totheir size, direction and spacing from each other.

Referring to FIG. 5, there is illustrated a gear arrange- 5. ment forthe driving connection between wheel 2 and the shaft 5 which providesfor a wider choice of available gear ratios than the arrangement shownin FIGS. 1 and 3. The arrangement is different from that of FIG. 3 inthat the gear r38 of FIG. 3 is replaced by a gear with two differentpitch radii, r38 and r38" respectively. The speed of the gear r9 isgiven by where n is the rotational speed of gear 35 and shaft 5. Thedirection of rotation of each of the gears is again indicated by arrowsand gear 9 rotates in opposite direction to gear 35 (and shaft 5).

FIG. 6 illustrates a specific gear train adapted to be operable as aclutch whereby the shafts 5 and It? may be completely separated fromeach other, a feature that is desirable when it is necessary to changethe transmission ratio to a predetermined value while the output shaftis held at zero speed. This is achieved by providing a separate flange60 which carries the shafts 57 of the transfer gears 56 that transmitpower between the gear 35 and 59. As long as this flange 60 isstationary, the operation of this gear train produces the same resultsas that of the gear train shown in FIG. 1. The flange 60 is rotatablyjournalled by its hub 61 in the bearing 29 of the housing wall 30, andit is held stationary by the brake band 62 acting upon the rim 63. Whenthe brake 62 is released, the transmission of power between the shaft 5and the wheel 2 is interrupted and the shaft 5 is free to rotate withouttransmitting any motion or power to the shaft 10. It is to be noted thatthe arnangement of gears as illustrated in FIG. 6 which includes aninternal gear 59 does not provide the flexibility of obtaining a verylarge number of different ratios between shaft 5 and the sleeve shaft 6(that is, the wheel 2), while in v the preferred form of FIG. 1 analmost unlimited numher of ratios can be obtained by a simple exchangeof idler gears in a manner similar to that of change gears driving thelead screw of a lathe.

FIG. 7 shows schematically the basic elements of FIG. 1, while leavingout the gear train 35, 36, 38, 9 since it is believed that the operationof this gear train, that is driving the wheel 2 at a reduced speed andin opposite direction with respect to wheel 1, is clearly understoodfrom the FIGS. 1, 3, and 5. In FIG. 7 the shaft 5 of FIG. 1 isrepresented by its geometrical axis S-S. The curved arrows denoted n I1and n each arrow is to be taken as passing with its heavy middle portionin front of its respective axis. Thus the wheel 1 rotates clockwise whenseen from the left side and has the rotational speed 11 (revolutions persecond); the wheel 2 rotates counter-clockwise (as seen from the left)with the speed 11 (rev.p.s.) and the disc 3 rotates around its axis 14with the angular velocity w counter-clockwise when seen from below (FIG.8). The arrow 11;, indicates the clockwise revolving motion of the axlel4and carrier 11 together with the disc 3 (and its thrust bearings shownin FIG. 1) around the axis SS, the numerical rotational speed being 11rev. per sec.

FIGS. 8 and 9 correspond to FIG. 4 in that size, direction and spacingof the vectors V and V is the same. They serve to further explain theoperation of the device and also to furnish proof that the output speedvaries in straight-line proportion to the relative displacement of thephysical center of the disc 3, in axial direction along the line X-X. Ithas been shown that the position of the epicenter is determined only bythe two vectors V and V In FIG. 8, the position of the disc center Ccoincides with the epicenter C (same as in FIG. 4 for the position ofthe disc marked 3). Under these conditions the rolling contact Cdescribes upon the disc surface a circular path with radius r1 and theangular velocity m Similarly, the contact point C describes a circularpath with radius r2 and the same angularspeed The relative position ofvector V with respect to vector V as well as their relative sizes arethe same as shown in FIG. 4. The position and inclination of the lineA-B likewise is the same as shown in FIG. 4.

It has been postulated that there shall be no slipping in the rollingcontacts C and C as between the periphery of the wheels 1 and 2 and thesurface of disc 3 respectively. Therefore, in point C the tangentialperipheral speed of wheel 1 must be the same as the tangential speed ofthe circular path with radius r1, that is, both are 1rd.n 1rd.n 7]. 12

Where to is the angle C C A and also the angle BBA if B'-C is made equalto B-C From thls last triangle it is seen further that w 1 2) r1+r2 an'dsince'r1+r2=L, that is the spacing between wheel 1 and 2 (to beaccurate, the distance between the respective central planes of rotationof the race tracks at the peripheries of the wheels 1 and 2), We find=tan (p d 0 1'i 2) f or, correctly, since n is negative:

d n=(m-( z))% This means that the angular velocity of the disc surfaceabout the epicenter is proportional to the algebraic difference of therotational speeds of the two wheels and inverse proportional to theirspacing L, their diameter al being a constant value. In FIG. 9 thephysical center of the disc 3 has been moved to the position denoted Cwhich is to the right of the epicenter C so as to be spaced therefrom bythe distance denoted 1'3. The speed vector for the surface speed, V isthe length C D and it is also Since V is smaller than V the difference VV forces the disc 3 to rotate with the angular velocity m about itsphysical center of rotation or axle center C the point C describing uponthe disc surface a circular path with radius rltl. The peripheral speed(or tangential speed at the point Ci) must be the equivalent of thespeed difference This means that the angular velocity of the disc 3around its physical center C and its physical axle 14 is constant and isidentical with the angular velocity of the disc surassess face aroundthe epicenter C irrespective of the position of the physical disc centerwith respect to the contact points C and C between the wheels 1 and 2and the disc 3. In other words, for a constant input speed 11,, therotational speed of the disc 3, (which is also the speed sustained bythe thrust bearing 15-16 in FIG. 1) is constant regardless of thechanging output speed of the transmission. This is one of the importantfeatures of the new structure according to this invention.

The above formula indicates furthermore that the rotational speed of thedisc 3 remains constant even for a changing speed n provided that thespeed n of the wheel 2 is changed simultaneously so that the sum n +nremains constant. The rotational speed 11 of the disc with axle l4 andthrust bearing 15, 16 around the axis S-S (FIG. 7) which is also thespeed of rotation of the output shaft 1% (PEG. 1) is the linear speed Vdivided by the circumference of the circular path of the center C aroundthe SS.

This can also be written as n =k.r3 where The above formula for 11proves the statement made earlier in connection with FIG. 4, namely,that for a con stant input speed n the output speed n3 is directlyproportional to the radius r3 that is, the displacement of the physicalcenter C of the disc 3 from the epicenter C When the disc center C isdisplaced to the left of the epicenter C as illustrated in FIG. 10, theradius r3 must be counted as negative and therefore the output speed 21is also negative, that is, the output shaft rotates in oppositedirection to the input shaft 5.

FIG. 12 illustrates a speed diagram for a structure in which the vectorV is again in opposite direction to V but of the same numerical size.The epicenter, being the intersection of the line AB with the axis X--Xis now located at C in the middle between C and C so that r1 is equal tor2, or /2L. When the disc is positioned with its center C coincidentwith C (position of disc marked in heavy line 3), the disc rotates aboutthe center C, but this center does not revolve around the axis SS andthe speed of the output shaft is zero. Displacing the disc to the rightto the position 3', which the center at C will produce a forward outputspeed n defined by Displacement of the disc 3- to the left of theepicenter C to the position C (disc denoted 3") will similarly produce areverse speed -n according to places the gear 35 on the shaft in FIG. 1and it meshes with the idler gear r136 which replaces the gear 36 (FIGS.1 and 3). The idler gear 136 meshes with idler gear r138 which replacesgear r38 in FIG. 5. Rigidly connected to r138 is the gear r138" whichmeshes with the gear r131 substituting for gear 9 in FIG. 1 and beingconnected to the wheel 2. If the ratio of r138/r138" is made the same asthe ratio r13tl/r131, the gear r131 (and with it wheel 2) rotates withthe same absolute speed but in opposite direction to the gear r130 (andshaft 5 plus wheel 1).

A transmission embodying the basic structure as illustrated in FIG. 12offers substantial advantages over integrators of the ball and disctype. It possesses a sharply defined zero point and it can be used atthis zero point under full load continuously without fatigue or wear dueto the destructive rubbing forces which develop at the zero point ofball-disc type integrators.

A still further modification of the basic principle of this invention isillustrated in FIGS. 13 and 14. In this arrangement both wheels 1 and 2are caused to rotate in the same direction. Inspection of FIG. 14 showsthat both speed vectors, V and V are positive, that is, going in thesame direction while being of difierent absolute value. The contactpoint of Wheel 1 is again denoted C and the speed vector V goes from Cto point A. Similarly, the speed vector V extends from the contact pointC to the point B. The axis X-X goes through the points C and C and thespacing between C and C is denoted L. The position of the epicenter isagain the point of intersection of the line A-B with the axis XX; sincethe vector V is smaller than vector V the intersection point C lies tothe left of point C In the drawing of FIG. 14, in order to save space,the point C is shown much nearer to point C its correct position wouldbe much farther to the left, and this shortening of the distance isindicated in the drawing by the broken lines A-B-C and XX. The distanceC C is again denoted 1'1 and the distance C -C is denoted T2. Inprevious diagrams which referred to FIGS. 1 and 7 through 11, the radiusr2 used as the distance C -C measured upon the axis X-X was a negativefigure because the distance was to the left of point In the present caseof FIG. 14 the radius r2 as distance between C and C is positive becauseit is to the right of C Therefore, the distance or spacing between C andC marked L (same as previously) is, using the same formula The linearspeed vectors for various positions of the physical disc center C uponthe axis X-X are again defined by the length of the speed vector betweenthe axis XX and the line A-B for each individual position of C between Cand C With the disc center at C in the middle between C and C the speedvector V is also midway between V and V the position of the disc 3 forthis position of the center being indicated by a heavy circle marked 3.The distance from C to the epicenter C is the radius r3 which determinesthe nu-. merical value of V as r340 Similarly, the lowest and highestoutput speed vector, V and V respectively, are found by multiplying therespective radii with the angular disc velocity ca and in like mannerthe output speeds can be found using the previously given formulae,provided that it is kept in mind that r2, 11 and V are now The positionsof the disc 3 belonging to the centers C and C respectively are markedby 3' and 3". The angular speed of rotation w of the disc 3 around itscenter and axle 14 are also obtained by the previous formula as Itfollows from this that for small differences between n and 12 the disc 3rotates very slowly around its axis while the output speed 11 may bevery close to m. This indicates that a substantial portion of power istransmitted to the output shaft through the revolving of the disc 3around the carrier axis SS (geometrical axis of shaft 5, FIG. 1) andonly a smaller portion of power is transmitted through rotation of thedisc 3 about its axle 14 and the rolling motion of the wheels upon thedisc. The result of these conditions is an extremely high eificiency ofpower transmission for structures in accordance with this design; incases where the speed range is limited to a variation of perhaps 10-15%of the output speed, the efliciency of power transmission may reachvalues of about 98% which is unquestionably a very high figure for avariable speed transmission.

FIG. 13 illustrates a gear train which may be used to provide a speedvector V going in the same direction as V (that is, positive) and at thesame time modified as to its absolute value according to the relationWhere in most of the foregoing descriptions reference was made to onedisc 3 only, it is to be understood that the explanations given applyequally to structures having two, three or more discs arrangedsurrounding the coaxial Wheels 1 and 2 (FIGS. 1 and 3) so as to be intractive rolling contact with the said wheels. Itis further understoodthat while the foregoing description refers to the pressure imposed uponthe rolling contacts substantially perpendicular to the contactingsurfaces as being obtained by an adjustable threaded nut 17 (FIG. 1)which transmits through the thrust bearing 15, 16 a radial inwardspressure to the disc 3, this detail is not to be considered an essentialpart of the new structure; and that any known method or design forobtaining a contact pressure between the disc surfaces and theperipheries of the wheels may be embodied in the structure without inany way altering or changing the basic principle of this invention orits novel operational features; and that such known methods or designsmay include devices in which the contact pressure is subject tomodification in accordance with the transmitted power, which designshave been described by way of example in my previous US. Patent2,057,482.

FIG. 15 discloses a structure which is in many respects similar to thatshown in FIG. 1; identical parts have been given the same referencenumbers. A control rod 101 engages through the shifting fork 72 theaxially slidable shift collar 22 and this establishes the basic control#1. The difference between FIG. 15 and FIG. 1 resides in the structureof the power transmitting connection between the wheel 2 and the shaft5. In FIG. 1 this connection is a gear train having a predeterminedfixed ratio. In FIG. 15 this connection comprises a transmission systemdenoted 150 which establishes a predetermined variable ratio between thegears and 138 respectively; gear 135 meshes with gear 35 on shaft 5 andgear 138 meshes with gear 9 which is connected to wheel 2. A control rod102 which changes the ratio of transmission 1.50 establishes the control#2 of the entire system and this control #2 may be operatedindependently of the control #1. While the variable ratio transmissionmay be of various designs, the speed control diagram shown in FIG. 16has been constructed with the postulate that the transmission 150 is ofthe same kind as the transmission illustrated in FIG. 1. (The onlydifference being that in the transmission 150 both input and outputshaft protrude concentrically at one side, which is a minor detail ofdesign not alfecting the operation.) The diagram in FIG. 16 illustratesonly one group of possible speed characteristics.

it is supposed that the transmission ft has a ratio range which permitsto set the speed vector V to any definite value between the limits ofplus V and minus V while the primary vector V remains unchanged. It isfurther postulated that minus V has the same absolute value as plus Vwhile the maximum value of plus V is smaller than plus V It is seen fromthe diagram that when the vector V is set to its negative maximum, thespeed characteristic for the control #1. delivers output speeds V goingfrom plus V through zero to minus V corresponding to an axial shiftingdisplacement of the center C of the disc 3 from the point C to the pointC This is identical to the speed diagram illustrated in FIG. 12 becausethe two basic speed vectors, V and V respectively, are of equal absolutevalue but of opposite direction. When the control #2 is operated so thatV changes from its negative maximum through zero to its positivemaximum, the output speed n (which corresponds to the speed vector Valso changes, the amount of such speed change depending .upon theposition of the disc center C relative to the contact points C and CWhen the disc center is at C the change in output speed will correspondto the change from vector V of the length C E to the vector V with thelength C -F, both being positive, which means that the output shaftrotates in the same direction as the input shaft. If in another examplethe disc center is in the position C the output speed changes correspondto the .change from vector minus V (C "G) to vector plus V (C "-H).

It is seen that the position of the line of characteristic, whichdetermines the size and direction of the output speed vector, is givenby the points A-B' for one extreme position of the control #2; and thatit is given by the points A-B" for the other extreme position of thecontrol #2. The first of these diagrams corresponds to that shown inFIG. 12 and the other to that shown in FIG. 14 respectively. Thestructure disclosed in FIG. 15 permits therefore to cover with a singleunit the control characteristics of both FIG. 12 and FIG. 14, and, inaddition, of all characteristics which fall between these two extremes.This change of the characteristic under which the control #1 operatescan be effected while the transmission unit is in operation andtransmitting power.

From another point of view, the transmission disclosed in FIG. 15 allowsthe operator to increase the rate of ratio change, that is the change ofratio per increment change of the basic control motion (control #1). Thereason for such modulation will be clearer from the followingconsiderations. Where it is desired to control the output speed in veryminute increments or steps, it is evidently advantageous to have acontrol system in which a fairly large amount of control motion producesonly a very small amount of change in the output speed. A control devicewith this characteristic is therefore less sensitive in its response toa given amount of control motion than a device wherein the same amountof control motion produces a greater change in output speed.

, If the transmission ratio is defined by and if we postulate V=constant and equal 1 then We have The increment of the control motion(or control travel) is the change which occurs in the distance C C SinceC -C is also r3 (the radius of the circular path of the For the point Eupon the characteristic AB the sensitivity S is then It is apparent thatthe sensitivity is the same for any point upon the line A-B because itis a straight line. Therefore it is clear that if the characteristicwere a curve, for instance a hyperbolic function, the sensitivity wouldvary from one point to the next.

It is now postulated that control #1 remains unchanged while control #2is shifted so that the vector minus V changes to plus V whereby thepoint B moves to the position B. The new characteristic A-B defines anew epicenter C and the new speed vector, denoted V extends from thepoint C to the point P. It is seen that the sensitivity for this newcharacteristic AB" is now V S %,=tan (02 Comparison with the previousvalue shows that the sensitivity has been reduced in the proportionFurthermore, the output speed has been changed in the proportion of sothat the new output speed 12 is now This change in output speed, ortransmission ratio, is objectionable in certain applications where it isdesired to change the sensitivity of the control mechanism withouthowever causing any change in the transmission ratio. A structure whichanswers to these requirements and which incor orates the basicprinciples of this invention is schematicaliy illustrated in FIG. 17;the speed diagrams pertaining thereto are shown in FIG. 18.

The transmission system comprises again two co-axially spaced wheels, 1and 2 respectively, the peripheries of which are connected or coupled bythe disc 3 which is rotatable upon the axle 14 extending radially andperpenso a dicnlar with respect to the co-axial shaft it). The axle l4is locked to the shaft iii through the carrier or hub 11 and the key114. T 16 thrust bearing i5, 16 causes the disc 3 to be pressed againstthe peripheries of the wheels 1 and 2, in accordance to the disclosureof FIG. 1. Each of the Wheels 1 and 2 is freely rotatable upon thecommon shaft 10, the wheel 1 is carried by a sleeve shaft 66 which atits right end has a gear 69; the wheel 2 is carried by a sleeve shaft 67which has at its left end a gear 9. The sleeve shafts 66 and 67 are alsoslidable axially upon the shaft 10 and are held in their axial positionsby bearings not illustrated. The shaft 141 is slidable axially withoutchanging the axial location of the wheel 1 and 2; it is provided with acollar 7% and a splined or geared portion The collar '70 is engaged bythe shifting fork i2 which can be moved by the control rod H1. Thisestablishes control #1 of the system. The splined portion 110 serves totransmit power from the output shaft independent of its axial position.

The input shaft H5 carries tWo gears, and 35 respectively; The gear 135is in power transmitting connection through the gear 136 with one sideof the variablespeed transmission 152 the other side of which isconnected through the gears 138 and 69 to the wheel 1. Sim ilarly,thegear 135' is connected through the gear 136 to the one side of thevariable ratio transmission 153 while the other side thereof is throughthe gears 138 and 9 connected to the wheel 2. The transmission 152 isratio controlled by the control rod 102 and the transmission 153 by thecontrol rod 103, thus establishing control #2 and control #3respectively. The transmission system illustrated in FIG. 17 hastherefore available three independent control movements, of which #1 isthe basic control shifting motion for the axial position of the physicalcenter of the disc (or discs) 3, while the other control motions, #2 and#3 allow for predetermined independent control of speed and direction ofrotation of the two wheels 1 and 2 respectively, thereby providing forpredetermined modulation of the two speed vectors V and V according tothe diagram FIG. 18. The size of the disc 3 and the spacing of thewheels 1 and 2 are illustrated at the same scale as was used for theprevious figures in order to facilitate a comparison between the variousdiagrams; it is however understood that the spacing L between the Wheels1 and 2 may be made variable and that the axial position of each of thewheels 1 and 2 may be determined individually by separate and additionalcontrol means so that a total of five independent control motions aremade available for control of the output speed.

The diagram of FIG. 18 clearly shows that even when the two wheels 1 and2 are spaced axially at a fixed distance L, the epicenter C may be movedto almost any position along the axis XX. In case where speed vector Vequals C -A and the vector V is equal to C -B the characteristic A r-B2determines the epicenter at C If under this condition the disc center isat C the output speed is represented by V equal to C -Q and thesensitivity S is G -A 02"'C1 mm W Changing the vector V to equal C A andthe vector V to equal C B results in a characteristic A B with theepicenter at C This characteristic goes also through the point Q of thespeed vector V and this means that the output speed 21 remainsunchanged. However, the sensitivity of the basic control motion #1 hasbeen changed and is now defined by C1 S 003* -tan as which is obviouslysmaller than S Therefore it is seen that the sensitivity of the controlsystem has been altered, or modulated, during operation of the systemwithout causing any change in ratio or the output speed of the completesystem. FIG. 18 further illustrates that the epicenter may be positionedon any point of the axis XX between C on the left to C on the right sideby appropriate modulation of the two input parameters V It is understoodthat while the foregoing specification and drawings are given asillustrative examples of preferred forms of embodiments of thisinvention, there are many other forms of structures in which the basicprinciple of this invention may be carried out. All of these formscomprise as basic elements three co-axially rotatable members, two ofwhich have tracks of identical diameters and are axially spaced fromeach other, while one is a carrier rotatable about the common axis andsupporting at least one disc freely rotatable about a radial axisperpendicularly intersecting the common axis and in traction contactwith the periphery of each of the axially spaced members so as to formtherebetween a rotatable coupling link, and a driving and a driven shaftone of which is in power transmitting connection with two of saidrotatable members, and control means for changing the relative axialposition between the radial axis of the disc with respect to thepositions of the axially spaced rotatable members.

Having thus described my invention and illustrated its use, what I claimis:

1. A variable ratio transmission:comprising two coaxially aligned wheelshaving peripheral race Ways of substantially identical diameters axiallyspaced from each other, at least one disc mounted rotatable about anaxis perpendicular and radial with respect to the geometric axis of saidwheels, said disc having a plan-e surface contacting tangentially saidrace ways, means adapted to impose pressure upon the contacts betweensaid plane disc surface and said race ways, an axially slidable carriersupporting said perpendicular axis rotatable. about said geometric axisof said wheels, means for shifting said carrier and said disc axiallywith respect to said wheels, 9. driving shaft and a driven shaft, powertransmitting means between both of said wheels and one of said shaftsarranged to cause rotation of said Wheels with a predetermined relationof speed with respect to each other and means adapted to transmit powerbetween said axially slidable carrier and the other shaft.

2. A variable ratio transmission system, comprising a carrier rotatableabout an axis and a pluralityof discs having flat surfaces and each discmounted upon said carrier rotatable about an individual axisperpendicularly intersecting said axis of the carrier so that the flatsurfaces of said discs are facing said axis of the carrier at the samedistance therefrom while symmetrically surrounding it, two individuallyrotatable members spaced from each other co-axial with saidcarrier-axis, each of said members provided with a circular peripheralrace surface in tractive rolling contact with said flat disc surfaces,control means for changing the relative axial position between saiddiscs and said peripheral race surfaces of said rotatable members, adriving and a driven shaft, a power transmitting direct connectionbetween one of said rotatable members and one of said shafts, and amodulating power transmitting connection between the same shaft and theother of said members whereby said rotatable members are caused torotate at a predetermined relation of speed andvdirection of rotationwith respect to each other, and a power transmitting connection betweensaid driven shaft and said carrier.

3. A variable ratio transmission system, comprising a carrier rotatableabout an axis, two independently rotatable members coxail therewith andeach provided with a peripheral race way of identical diameter withrespect to each other, a plurality of discs having flat surfacesparallel to said axis of the carrier, said discs being mounted upon saidcarrier rotatable about individual axes which intersect the axis of saidcarrier. at right angles thereto and all of said individual axespositioned in a single plane perpendicular to said carrier axis, saidflat surfaces of the discs positioned tangentially surroundmg saidperipheral race ways of said independentlyrotah able members andintractive rolling contact with said race ways, means adapted tomaintain the required pres sure in said rolling contacts, said rotatablemembers positioned in axially spaced relation to each other in suchmanner that said race ways are placed on opposite sides of said singleplane which contains said individual disc axes, a driving and a drivenshaft, power transmitting means between. one of said shafts and each ofsaid rotatable members adapted to individually control the respectivespeed and direction of rotation of each of said rotatable members, and apower transmitting connection between said rotatable carrier and theother of said shafts. V

4. In a variable ratiotransmission system having a primary control meansfor changing the transmission ratio and secondary control means forchanging the sensitivity of said primary control means, twoindependently rotatable race ways axially spaced fromeach other upon acommon geometrical axis, at least one disc having a fiat surfacetangentially contacting said race ways in two tractive rolling contactsand mounted freely rotatable upon an axis which is parallel to theplanes of rotation of said two race ways and positioned therebetween inspaced relation to each of said two planes of rotation, a carrier freelyrotatable upon said common geometrical axis and adapted to support saiddisc axis together with said disc rotatable thereon whereby said disc inaddition to being freely rotatable upon its own axis is also capable ofsimultaneous rotation together with said carrier about said commongeometrical axis, a primary control means adapted to cause axialdisplacement of said carrier and said disc relatively to said planes ofrotation of said race Ways whereby the respective distances between saiddisc axis and said planes of rotation of the race Ways are inverselychanged, a driven shaft connected to said carrier, a driving shaft, twopower transmitting connections including variable speed control meansinterposed between said driving shaft and each one of said race waysrespectively, said last named control means being operable independentlyof said primary control means at a predetermined relation to each otherwhereby the sensitivity of said primary control means may be alteredwithout affecting the ratio defined by the setting of the primarycontrol means.

5. A variable ratio transmission sstem comprising a driving and a drivenshaft, two co-axially spaced rotatable raceways of substantially equaldiameters, power transmitting means arranged between one of said shaftsand both of said raceways respectively whereby said raceways are causedto rotate in a predetermined relation of speed and direction of rotationwith respect to each other, a plurality of discs with flat surfacesfreely rotatable about individual axes, said fiat surfaces contactingboth of said raceways in tractive rolling contacts, a carrier supportingsaid individual axe so arranged that all of said axes are positioned inone plane parallel to and interspaced between the planes of rotation ofsaid two raceways, a power transmitting connection between said carrierand the other of said shafts, and control means for axially shiftingsaid carrier relative to said race ways whereby the position of saidplane of said disc axes is changed relative to said planes of rotationof said race ways.

6. In a variable ratio transmission system, a driving and a drivenshaft, two race ways of identical diameters independently rotatableabout a common geometrical axis at a predetermined spacing from eachother, a direct drive connection between one of said race ways and oneof said shafts, a power transmitting connection having a predeterminedchangeable ratio between said same shaft and the other of said raceways, at least one fiat disc freely rotatable about an axisperpendicularly intersecting said common axis and in tractive rollingcontact with both of said race ways, a carrier supporting said disc axisfreely rotatable about the common axis of said race ways and meansslideably connecting said carrier to the other of said shafts.

7. L1 a variable ratio transmission system, two co-axially spacedrotatable race ways, a driving and a driven shaft, means in drivingconnection with one of said shafts adapted to cause said race ways tomaintain a predetermined relation of speed and direction of rotationwith respect to each other, at least one freely rotatable couplingelement in tractive rolling contact with each of said race ways andhaving its axis of rotation positioned between said spaced race ways, acarrier for said coupling element, said carrier being rotatableco-axially with said race Ways, control means connected to said carrieradapted to cause a change of the ratio of rotational speed between saidcarrier and at least one of said race ways and a driven shaft connectedto said carrier.

8. In a variable ratio transmission system, a carrier rotatable about anaxis, a disc with a flat surface being supported by said carrierrotatable about the center of said disc so that the fiat surface of thedisc is substantially parallel to the axis of said carrier, twoco-axially rotatable members, each of said members having a peripheralrace way with a diameter substantially equal to twice the distancebetween said flat surface of the disc and the axis of said carrier,means adapted to cause tractive rolling contact between said race waysand said flat disc surface substantially in two points of said surfacewhich are spaced from each other and positioned upon a straight linethrough the center of rotation of said disc and which line is parallelto said axis of said carrier, driving and driven shafts, apower-transmitting connection between one of said shafts and saidcarrier, means for transmitting rotary power in predetermined selectiveratio and direction of rotation individually between each of saidco-axially rotatable members and another of said shafts, whereby saidtractive rolling contacts transmit to said disc surface in each of saidcontact points a speed vector of predetermined size and direction, andcontrol means adapted to vary the position of said center of rotation ofthe disc relatively to said points.

9. A variable ratio transmission system, comprising a carrier rotatableabout an axis and a plurality of freely rotatable bodies mounted uponsaid carrier, each of said bodies having a substantially flat surfaceand being rotatable upon an individual axis, all of said last named axesbeing positioned in one common plane and so as to intersect the axis ofsaid carrier in one common point, said flat surfaces being positionedsubstantially symmetrically with respect to said common point, twoindependently rotatable race ways co-axial with said axis of saidcarrier and in tractive rolling contact with the flat surfaces of saidrotatable bodies, means for maintaining the tractive rolling contactbetween said race ways and the fiat surfaces of said bodies, controlmeans for changing the axial position of said common plane of said axeswith respect to said race ways, a driving and a driven shaft, a powertransmitting connection between one of said race ways and one of saidshafts, a modulating power transmitting connection between the same saidshaft and the other of said race ways whereby said co-axial race waysare caused to rotate at a predetermined relation of speed and directionof rotation with respect to each other, and a power transmittingconnection between said driven shaft and said carrier.

19. In a variable ratio transmission system, a driving and a drivenshaft, a pair of race ways of substantially equal diameters co-axiallyspaced from each other and independently rotatable about their commonaxis, torque transmitting connections between one of said shafts andeach of said race ways, at least one of said connections includingindependently operable control means for mod- 7 ulating speed anddirection of rotation of the respective race way, at least onedifferential member having a substantially flat surface and beingrotatable about an axis perpendicularly intersecting said common axis,said fiat surface positioned to maintain tractive rolling contact witheach of said race ways, a carrier supporting said differential memberfor free planetary motion about said common axis, and power transmittingmeans between said carrier and the other of said shafts.

11. In a variable ratio transmission system, two coaxially spacedindependently rotatable race ways, a driving and a driven shaft, meansin driving connection with one of said shafts and at least one of saidrace Ways adapted to maintain a predetermined relation of speed anddirection of rotation of said race ways with respect to each other, atleast one freely rotatable differential coupling element in tractiverolling contact with each of said raceways and having its axis ofrotation positioned perpendicular to that of said spaced race ways, acarrier including journalling means for rotatably supporting saidcoupling element, means supporting said carrier rotatable about thecommon axis of said co-axial race ways, an axially slidable powertransmitting connection between said carrier and said driven shaft, andmeans adapted to vary the axial position of the axis of rotation of saidcoupling element relatively to said race ways.

12. A variable ratio transmission system comprising, an input shaft, anoutput shaft, two drive wheels of equal diameters mounted for rotationabout a common axis, means providing a continuous driving connectionbetween said input shaft and both of said drive wheels, a differentialwheel in continuous tractive rolling contact with both of said wheels,said differential wheel being mounted for free rotation about a furtheraxis intersecting said common axis, and means connected to saiddifierential wheel for transmitting the rotational movement of saidfurther axis with respect to said common axis to said output shaft.

13. A transmission system according to claim 12, wherein said meansproviding said continuous driving connection includes means for causingsaid drive wheels to rotate in opposite directions and at apredetermined difference of speed.

14-. A transmission system according to claim 12 wherein said meansproviding said continuous driving connection includes an independentlyoperable control means for varying the relation of speed and directionof rotation between said two drive wheels during the operation of saidtransmission system whereby the sensitivity of the speed control of saidsystem may be altered without causing a change in the transmission ratiobetween said driving and said driven shaft.

15. A transmission system according to claim 12 wherein said axes aremutually perpendicular and said difierential wheel is mounted for axialdisplacement of said further axis along said common axis, and said meansproviding said continuous driving connection including control meansoperable independently of said displacement of said further axis forvarying the relation of speed and direction of rotation of at least oneof said drive wheels with respect to the said input shaft during theoperation of said transmission system whereby the control characteristicof said system may be altered without interrupting the transmission ofpower through said system.

16. A variable ratio transmission system, comprising an input shaft, twoco-axially aligned drive wheels of equal diameters, means providing acontinuous driving connection between both of said wheels and said inputshaft, an output shaft axially aligned with said drive wheels, adifferential wheel carried by said output shaft for rotation therewith,said ditterential wheel being mounted for free rotation about an axisintersecting the rotational axis of said aligned shafts, and meansmaintaining said differential wheel in continuous tractive engagementwith both of said drive wheels.

17. A variable ratio transmission system according to claim 16, whereinsaid diflferential wheel has a sub stantially flat face in tractiverolling engagement with said drive wheels and its rotational axis isdisplaceable axially of said shafts for varying the ratio of saidtransmission system, said means providing said driving connectionbetween said drive wheels and said input shaft including means forreversing the direction of rotation of one of said drive wheels withrespect to the other.

References Cited by the Examiner UNITED STATES PATENTS 1,576,399 3/26Aymard 74--691 FOREIGN PATENTS 452,422 8/36 Great Britain.

DON A. WAITE, Primary Examiner.

1. A VARIABLE RATIO TRANSMISSION COMPRISING TWO COAXIALLY ALIGNED WHEELSHAVING PERIPHERAL RACE WAYS OF SUBSTANTIALLY INDENTICAL DIAMETERSAXIALLY SPACED FROM EACH OTHER, AT LEAST ONE DISC MOUNTED ROTATABLEABOUT AN AXIS PERPENDICULAR AND RADIAL WITH RESPECT TO THE GEOMETRICAXIS OF SAID WHEELS, SAID DISC HAVING A PLANE SURFACE CONTACTINGTANGENTIALLY SAID RACE WAYS, MEANS ADAPTED TO IMPOSE PRESSURE UPON THECONTACTS BETWEEN SAID PLANE DISC SURFACE AND SAID RACE WAYS, AN AXIALLYSLIDABLE CARRIER SUPPORTING SAID PERPENDICULAR AXIS ROTATABLE ABOUT SAIDGEOMETRIC AXIS OF SAID WHEELS, MEANS FOR SHIFTING SAID CARRIER AND SAIDDISC AXIALLY WITH RESPECT TO SAID WHEELS, A DRIVING SHAFT AND A DRIVENSHAFT, POWER TRANSMITTING MEANS BETWEEN BOTH OF SAID WHEELS AND ONE OFSAID SHAFTS ARRANGED TO CAUSE ROTATION OF SAID WHEELS WITH APREDETERMINED RELATION OF SPEED WITH RESPECT TO EACH OTHER AND MEANSADAPTED TO TRANSMIT POWER BETWEEN SAID AXIALLY SLIDABLE CARRIER AND THEOTHER SHAFT.